Manufacture of artificial stone.



NITED STATES Patented December 13, 1904.

PATENT OFFICE.

MANUFACTURE OF ARTIFICIAL STONE...

SPECIFICATION forming part of Letters Patent No. 777,1d5, dated December13, 1904.

Application filed May 8,1903. Serial No. 156,281. -(No mode To all'mhont it nm/y concern:

Be it known that I, CARL RUBrrscHUNe, a subject of the German Emperor,residing at Frankfort-on-the-Main, Germany, have invented certain newand useful Improvements in the Manufacture of Artificial Stone, of whichthe following is a specification.

This invention relates to improvements in the manufacture of artificialstone.

The method of manufacturing hard artificial stone by mixing andsubsequently pressing in molds divided stony material and tar which havepreviously been separately heated is known. With this method the valueof the product principally depends, on one hand, on the use of theproper proportions of filling material and tar, the percentage of theformer being as high as possible, live to ten times the weight of thetar, and, on the other hand, on using tar of the proper consistency, sothat the said tar is able to take up large quantities of fillingmaterial and provide the necessary adhesive strength for the same. Thepractical employment of this method on a large scale has disclosed animportant drawback, which consists in the fact that it is very difficultto uniformly compress large quantities of the mixture in a set of molds,sinceif the later charges are subjected to the same pressure as theearlier ones the molds areliable to break. The cause of this fact whichwas long unexplained, is that the mixture in the mixing apparatusgradually and almostimperceptibly cools, and thus loses plasticity andcompressibility. in order to obtain uniformity with large batches, it isnecessary to charge the molds with a uniform material, so that thedecreased plasticity and compressibility ultimately has the effectmentioned. To avoid this effect in my improved method, the divided stonematerial is heated in a separate apparatus to a considerably higherdegree than the tar-for instance, to 200 or 300 centigrade or more-sothat it becomes completely dry. The tar, on the other hand, is after being freed from ammonia liquor heated to a temperature below thatofapproximately 160 to 1550 centigrade, which it is desired that themixture should have. The heating of the two materials takes place inseparate vessels, from which they continuously flow or are moved to themixing apparatus in the desired proportions. During the mixing thehotter particles of stone powerfully absorb the hot liquid tar, and bythis means and by the thin film of tar with which they become coated areparticularly well fitted to cohere to the surrounding particles ofstone. The hotter stone also contributes heat to the tar during theprogress of the process of mixing and brings it to the temperaturerequired for its most beneficial action. By this means with outoverheating the tar at any time the period at which the tar reaches theheat desired for it is removed from the period antecedent to the mixingand occurs during the mixing--that is to say, it is nearer to the periodof delivery to the mold. The mass is continuously and automaticallyfedto the molds by the mixing apparatus :in proportion as it is formed, sothat uniform mixing proportions, charges, and temperature are insured,and consequently uniform moldings.

I declare that what .I. claim is- The process of manufacturing moldedartificial stone consisting in separately heating divided stony matterto a temperature above 180 centigrade and tar to a temperatureequivalently below 150 centigrade, feeding said stony material and tartogether in their respectively-heated states in definite proportions,mixing same, whereby the hotter stone imparts heat to the tar andcontinues the distillation thereof, feeding the product proportionatelyas it is formed to molds and compressing same therein.

In witness whereof I have signed this specilication in the presence oftwo witnesses.

CARL RUBITSCH UNG.

WVitnesscs:

JEAN Grimm), CARL G-nunn.

